Answer:
a) x4 b) Eyepiece x10 Objective x40
Step-by-step explanation:
a) x4 magnification
The 4x objective lens has the lowest power and, therefore the highest field of view. As a result, it is easier to locate the specimen on the slide than if you start with a higher power objective.
b)
Eyepiece Lens: the lens at the top of the microscope that you look through. The eyepiece is usually 5x, 10x or 15x power.
Objective Lenses: Usually you will find 3 or 4 objective lenses on a microscope. They almost always consist of 4x, 10x, 40x and 100x powers.
To get 400 we need to use a combination that, multiplied together, will give us 400.
If the eyepiece lens is 10x then 400/10 = 40
So if we use the 10x Eyepiece lens with the 40x Objective Lens we will get a total magnification of x400.